1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Stack trace management functions 4 * 5 * Copyright (C) 2022 Loongson Technology Corporation Limited 6 */ 7 #include <linux/sched.h> 8 #include <linux/stacktrace.h> 9 #include <linux/uaccess.h> 10 11 #include <asm/stacktrace.h> 12 #include <asm/unwind.h> 13 14 void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, 15 struct task_struct *task, struct pt_regs *regs) 16 { 17 unsigned long addr; 18 struct pt_regs dummyregs; 19 struct unwind_state state; 20 21 if (!regs) { 22 regs = &dummyregs; 23 24 if (task == current) { 25 regs->regs[3] = (unsigned long)__builtin_frame_address(0); 26 regs->csr_era = (unsigned long)__builtin_return_address(0); 27 } else { 28 regs->regs[3] = thread_saved_fp(task); 29 regs->csr_era = thread_saved_ra(task); 30 } 31 regs->regs[1] = 0; 32 regs->regs[22] = 0; 33 } 34 35 for (unwind_start(&state, task, regs); 36 !unwind_done(&state); unwind_next_frame(&state)) { 37 addr = unwind_get_return_address(&state); 38 if (!addr || !consume_entry(cookie, addr)) 39 break; 40 } 41 } 42 43 int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry, 44 void *cookie, struct task_struct *task) 45 { 46 unsigned long addr; 47 struct pt_regs dummyregs; 48 struct pt_regs *regs = &dummyregs; 49 struct unwind_state state; 50 51 if (task == current) { 52 regs->regs[3] = (unsigned long)__builtin_frame_address(0); 53 regs->csr_era = (unsigned long)__builtin_return_address(0); 54 } else { 55 regs->regs[3] = thread_saved_fp(task); 56 regs->csr_era = thread_saved_ra(task); 57 } 58 regs->regs[1] = 0; 59 regs->regs[22] = 0; 60 61 for (unwind_start(&state, task, regs); 62 !unwind_done(&state) && !unwind_error(&state); unwind_next_frame(&state)) { 63 addr = unwind_get_return_address(&state); 64 65 /* 66 * A NULL or invalid return address probably means there's some 67 * generated code which __kernel_text_address() doesn't know about. 68 */ 69 if (!addr) 70 return -EINVAL; 71 72 if (!consume_entry(cookie, addr)) 73 return -EINVAL; 74 } 75 76 /* Check for stack corruption */ 77 if (unwind_error(&state)) 78 return -EINVAL; 79 80 return 0; 81 } 82 83 static int 84 copy_stack_frame(unsigned long fp, struct stack_frame *frame) 85 { 86 int ret = 1; 87 unsigned long err; 88 unsigned long __user *user_frame_tail; 89 90 user_frame_tail = (unsigned long *)(fp - sizeof(struct stack_frame)); 91 if (!access_ok(user_frame_tail, sizeof(*frame))) 92 return 0; 93 94 pagefault_disable(); 95 err = (__copy_from_user_inatomic(frame, user_frame_tail, sizeof(*frame))); 96 if (err || (unsigned long)user_frame_tail >= frame->fp) 97 ret = 0; 98 pagefault_enable(); 99 100 return ret; 101 } 102 103 void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie, 104 const struct pt_regs *regs) 105 { 106 unsigned long fp = regs->regs[22]; 107 108 while (fp && !((unsigned long)fp & 0xf)) { 109 struct stack_frame frame; 110 111 frame.fp = 0; 112 frame.ra = 0; 113 if (!copy_stack_frame(fp, &frame)) 114 break; 115 if (!frame.ra) 116 break; 117 if (!consume_entry(cookie, frame.ra)) 118 break; 119 fp = frame.fp; 120 } 121 } 122